1. Technical Field
The present disclosure relates to a wiring board, and a semiconductor device.
2. Description of the Related Art
In the related art, as a wiring board on which an electronic component such as a semiconductor chip can be mounted, there has been known a wiring board in which a plurality of wiring layers and a plurality of insulating layers are provided on one another alternately by a build-up method on opposite upper and lower surfaces of a core substrate in order to increase the density of wiring patterns. As this kind of wiring board, there has been proposed a wiring board in which a low-density wiring layer including an insulating layer made of a thermosetting resin is formed on a core substrate, and a high-density wiring layer including an insulating layer made of a photosensitive resin is formed on the low-density wiring layer (e.g. see JP-A-2014-225632).
In recent years, an increase in the density of electronic components which can be mounted on the wiring board and reduction in the size of each electronic component have been advanced more greatly, and a request for reducing the size and the thickness of the wiring board has been further increased. When the thickness of the core substrate of the wiring board is reduced in order to satisfy such a request, mechanical strength of the core substrate is however lowered. Therefore, there arises a problem that rigidity of the wiring board is lowered and warping is apt to occur in the wiring board.